Easily-cleanable filters

ABSTRACT

A filter including a plurality of filter discs each formed with a central opening and disposed in a stack within a filter housing with the side faces of adjacent discs contacting each other for filtering the fluid flowing through the housing from its inlet to its outlet, the filter discs being maintained in a stack by a plurality of axially-extending rods arranged in a circular array around the outer faces of the discs and circumferentially spaced from each other to permit the filter disc stack to be cleaned by passing a cleaning nozzle through the central openings of the filter discs in the stack.

.Iadd.

This application is a continuation of application Ser. No. 07/148,211,filed Jan. 25, 1988 now abandoned. .Iaddend.

BACKGROUND OF THE INVENTION

The present invention relates to easily cleanable filters, andparticularly to filters of the multiple disc type.

The multiple-disc type filter is now widely used in a number ofdifferent applications for filtering fluids, particularly for removingdirt particles in water irrigation systems. Briefly, this type filterincludes a plurality of filter discs disposed in a stack within thefilter housing, with the side faces of adjacent discs being ribbed andcontacting each other to provide a large number of narrow passages forfiltering the fluid flowing through the stack of discs in the radialdirection. Cleaning the filter may be done manually by opening thefilter housing and rinsing the discs with a water spray or automaticallyby including a backwash nozzle which is automatically made operative bya differential-pressure device sensing the pressure drop across thestack of filter discs.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a multiple-disc typefilter having an improved construction which better facilitates cleaningthe filter, particularly when the filter is automatically cleaned by abackwash nozzle.

According to a broad aspect of the present invention, there is provideda filter including a housing having an inlet and an outlet, and aplurality of filter discs each formed with a central opening and alldisposed in a stack within the housing with the side faces of adjacentdiscs contacting each other for filtering the fluid flowing through thehousing from its inlet to its outlet; characterized in that the filterdiscs are maintained in a stack by a plurality of axially-extending rodsarranged in a circular array around the outer faces of the discs andcircumferentially spaced from each other to permit the filter disc stackto be cleaned by passing a cleaning nozzle through the central openingsof the filter discs in the stack.

Further features and advantages of the invention will be apparent fromthe description below.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 illustrates one form of filter constructed in accordance with thepresent invention;

FIG. 2 is a transverse section along the lines II--II of FIG. 1;

FIG. 3 illustrates one form of cleaning nozzle which may be used in thefilter of FIG. 1; and

FIG. 4 illustrates another type of multiple-disc filter constructed inaccordance with the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The filter illustrated in FIG. 1 comprises a housing 2 including aninlet 4 connectable to an upstream supply pipe 6 for the pressurizedwater (or other fluid) to be filtered, and an outlet 8 connectable tothe downstream pipe 10 for the filtered water. Disposed within housing 2is the filter body 12 in the form of a stack of circular filter discs14, each of which discs is formed with a central opening 16. As notedearlier, such filter discs include ribbed side faces which contact eachother to provide a .[.larger.]. .Iadd.large .Iaddend.number of narrowpassages for filtering the water as it flows radially inwardly from theinlet 4 to the outlet 8, the edges of the large central openings 16 ofthe discs constituting the inner or downstream face of the filter body.Since such filter discs are now well-known further details of theirconstruction are not deemed necessary.

In the usual construction, however, the filter discs 14 are supported attheir .[.control.]. .Iadd.central .Iaddend.openings 16 by a pipe orcage, with the outer or upstream faces of the discs presenting arelatively smooth surface. Such a construction is particularly used inthe self-cleaning type filters which include a cleaning nozzle since thecleaning nozzle is usually located very close to the other faces of thefilter discs in order to more effectively draw out by suction the dirtparticles accumulating on the outer faces of the discs.

In the present invention, however, the filter discs 14 are secured inthe form of the stack by a plurality of rods 20 arranged in a circulararray around the outer faces of the discs and extending axially throughthe filter housing 2. These rods 20 are circumferentially spaced fromeach other to permit the discs to be cleaned by passing a cleaningnozzle 22 through the central openings of the discs 14 in the stack 12.Thus, the stack 12 of discs presents an inner cylindrical surface whichis substantially smooth and uninterrupted for accommodating the cleaningnozzle 22 and permitting it to be moved axially through the stack veryclose to the inner surfaces of the discs.

Cleaning nozzle 22 is not of the conventional suction type which drawsout the dirt particles by suction, but rather is of a pressurized typewhich blows out the filter particles from between the filter discs. Thecleaning nozzle is thus connected by a pipe 24 to the supply pipe 6 forfeeding to the nozzle the same fluid, namely water, which is filtered bythe filter body 12. Pipe 24 connecting nozzle 22 to the upstream supplypipe 6 is controlled by a value V₃ so that the pressurized water issupplied to nozzle 22 only during the cleaning operation, and not duringthe normal filtering operation.

The illustrated filter includes a further valve V₁ connected betweenhousing outlet 8 and the downstream pipe 10, which valve is open duringthe normal filtering operation but closed during the cleaning operation.Housing 2 further includes a dirty-water purging outlet 26, and afurther valve V₂ between that outlet, the housing inlet 4, and theupstream supply pipe 6. Valve V₂ is in the full-line positionillustrated in FIG. 1 during a normal filtering operation for directingthe water from the upstream pipe 6 to the filter inlet 4, but is movedto the broken-line position illustrated in FIG. 1 during a cleaningoperation in order to disconnect the housing inlet 4 from the upstreamsupply pipe 6, but to connect same to the dirty-water outlet 26.

During a cleaning operation, the filter nozzle 22 is moved axiallywithin the filter body 12 by means of a stem 30 connected to a piston 32displaceable within a cylinder 34 fixed to the valve housing 2. Piston32 is displaced by the pressure of the water within supply pipe 6controlled by a further valve V₄ such that during a cleaning operationpressurized water is supplied into an inlet port 35 at one side ofpiston 32 to move nozzle 22 in one direction (leftwardly in FIG. 1), andthen into another port 36 to move the piston in the opposite direction.

All the foregoing valves are controlled by a mode selector, generallydesignated by box 40, which may be controlled to effect either a normalfiltering mode of operation during which the filter body 12 filters outdirt particles carried by the water as the water passes through thefilter from its inlet 4 to its outlet 8, or a cleaning mode of operationduring which nozzle 22 cleans the filter body 12 of the dirt particulesaccumulated therein.

Filter housing 2 is mainly constituted of a cylindrical wall 42 formedwith an opening 44 at its juncture with the inlet 4, which cylindricalwall is closed by a pair of end walls. One end wall 46 is formed with anopening 48 at its juncture with the outlet 8, and with aninwardly-extending annular rib 50 for removably receiving within it endring 52 of the filter stack body 12. The opposite end wall 54 isremovable and is also formed with an inwardly-extending annular rib 56for receiving an end ring 58 at the opposite end of the filter stack 12.The rods 20 are secured to the two end rings 52 and .[.56.]. .Iadd.58.Iaddend.and are fixed thereto by fasteners 60.

It will thus be seen that the filter stack assembly 12, including thefilter discs 14, rods 20, and the end rings 52 and 58, may be insertedwithin the housing 2 and supported as an assembly by annular ribs 50 and56 of the two end walls 46 and 54, respectively, of the housing. Thefilter discs 14 may be cleaned within the housing 2 by the use of thecleaning nozzle 22, or may be removed from the housing by removing endwall 54 and then sliding out the assembly as a unit, for more thoroughcleaning if desired.

One form of cleaning nozzle 22 which may be used is shown if FIG. 3,wherein it will be seen that it includes two outlets 64, 66 both issuingjets at substantially right angles to each other. Outlet 64 iseccentrically mounted so that jet issuing therefrom will apply a rotarymoment to the nozzle 22 to rotate the nozzle within the filter discassembly 12 during the cleaning operation.

The filter illustrated in FIGS 1-3 may be operated as follows:

During a normal filtering mode of operation, as selected by the modeselector 40, the latter controls the various valves, as follows: ValveV₁ is opened, thereby connecting the filter outlet 8 to the downstreampipe 10; valve V₂ is moved to its full-line position, thereby connectingthe upstream supply pipe 6 to the filter inlet 4, and disconnecting thelatter to the dirty water outlet 26; valve V₃ is closed, therebyinterrupting the supply of pressurized water to the cleaning nozzle 22;and valve V₄ is closed, thereby interrupting the flow of water to thepiston 32 drive for the cleaning nozzle 22. Accordingly, during thisoperation, the water from supply pipe 6 will be fed through the filterinlet 4, through the stack 12 of filter .[.disc.]. .Iadd.discs.Iaddend.14, and then through the outlet 8 to the downstream pipe 10.

Whenever the stack 12 of filter discs is to be cleaned, mode selector 40is moved to effect a cleaning mode of operation, whereupon the valvesare controlled as follows: Valve V₁ is closed to interrupt the flow ofwater from the housing outlet 8 to the downstream pipe 10; valve V₂ ismoved to the broken-line position, thereby disconnecting the supply pipe6 from the housing inlet 4, and connecting the latter to the dirty-wateroutlet 26; valve V₃ is opened, thereby supplying pressurized water viapipe 24 to the cleaning nozzle 22; and valve V₄ is opened, therebysupplying pressurized water first to port 34 at one side of piston 32,and then to port 36 at the opposite side to effect a reciprocatorymovement of cleaning nozzle 22. During this mode of operation, thecleaning nozzle 22 is reciprocated along the inner surface of the stack12 of filter discs 14 by piston 32, and is also rotated by the reactionforce from its eccentric outlet 64, so as to apply pressurized water tothe complete inner face of the stack of discs and thereby to blow outthe dirt particles accumulating between the discs. These dirt particlesare washed out through the dirt-purging outlet 26.

It will be appreciated that mode selector 40 can be operated eithermanually, or automatically, e.g. by sensing the pressure drop across thefilter stack 12 and, upon sensing a predetermined pressure dropindicating a large accumulation of diet particles, automaticallyswitching the system from the normal filtering mode to the cleaningmode, as described above.

It will also be appreciated that the stack 12 of filter discs 14 may beconveniently removed as an assembly by merely removing end wall 54 andslipping out the assembly from the filter housing 2, whereupon thefilter discs 14 may also be cleaned as an assembly, or may be separatedfor more thorough cleaning.

FIG. 4 illustrates another embodiment of the invention particularlyuseful for manual cleaning of the filter discs in the stack by removingthem from the housing. Thus, the housing 102 also includes an inlet 104,an outlet 108, an end wall 146 fixed at one end of the housing, and aremovable end wall 154 at the opposite end. The stack 112 of filterdiscs 114 is also supported as an assembly by means of a plurality ofaxially-extending rods 120 arranged in a circular array around the outerfaces of the discs 114 of the stack 112, and secured at one end to endring 152 supported by annular rib 150 fixed to the housing end wall 146.Rods 120 are supported at their opposite ends by being received withinopenings formed in the removable end wall 154. The latter end wall isnormally secured to the end of housing 102 by a clamp 160 having anenlarged head 162 at its outer end, with its inner end being threadedthrough an opening in a rod 164 whose opposite ends pass throughopenings in a pair of brackets 166 fixed to the opposite sides of thehousing 102.

Thus, whenever it is desired to open the filter housing 102 for cleaningthe stack 112 of filter discs 114, it is only necessary to remove clamp160 and then remove rod 164, which thereby permits the housing end wall154 to be removed to provide access into the interior of the filterhousing. The stack 112 of discs 114 may be removed with end wall 154 asan assembly, or the end wall 154 may first be removed and the discs 114of the stack 112 may then be individually removed.

While the invention has been described with respect to two preferredembodiments, it will be appreciated that many other variations,modifications, and applications of the invention may be made.

What is claimed is:
 1. A filter includinga housing having an inlet, anoutlet, and a dirt-purging opening; a plurality of circular filter discsin said housing with each disc being formed with a central opening, andall the discs being disposed in a stack with the side faces of adjacentdiscs contacting each other for filtering the fluid flowing through thehousing from its inlet to its outlet; a pair of end rings at theopposite ends of said stack of filter discs and of larger outer diameterthan said filter discs, said end rings being formed with a plurality ofopenings therethrough around a circle of larger diameter than saidfilter discs; a circular array of axially-extending rods passing throughsaid openings in said end discs and circumferentially-spaced from eachother; the outer surfaces of said filter discs constituting upstreamside of the filter discs and facing said housing inlet and dirt-purgingopening, and the inner surfaces of said filter discs defined by theircentral openings constituting the downstream side of the filter stackand facing said housing outlet; and a cleaning nozzle movable axiallywithin said central openings of the filter discs for cleaning the filterdisc stack, said cleaning nozzle including means for connecting it to apressurized source of the fluid to be filtered for blowing out thefiltered particles from between the filter discs in the stack throughsaid circumferential spaces between the axially-extending rods and saiddirt-purging opening, said cleaning nozzle also including means foroutletting a fluid jet eccentric to the axis of the nozzle so as torotate the nozzle by the reaction force applied thereto by saideccentric jet.
 2. The filter according to claim 1, wherein said cleaningnozzle outlets fluid in the form of a jet and includes means forrotating the nozzle at the time of the issuance of the jet.
 3. Thefilter according to claim 2,further including a mode selector forselecting either a filter mode of operation or a cleaning mode ofoperation and valve means effective during the .[.cleaning.]..Iadd.filter .Iaddend.mode of operation to direct the fluid from saidhousing inlet through the filter stack to the housing outlet, and duringthe cleaning mode of operation to direct the fluid through the nozzle,the filter stack, and out through said dirt-purging opening in thehousing. .Iadd.
 4. A filter comprising:a housing having an inlet and anoutlet opening; a filter element disposed in said housing and having acentral longitudinal axis, said filter element having a central openarea arranged along said longitudinal axis of said filter element, aninner surface surrounding said central open area and an outer surface,the outer surface defining an upstream side of the filter element andthe inner surface of the filter element defining the downstream side ofthe filter element; a cleaning nozzle for emitting a pressurized fluidjet, said cleaning nozzle being disposed within said central open areaand communicating with a source of pressurized fluid; means forimparting rotation to said cleaning nozzle by outletting aneccentrically directed fluid jet such that the cleaning nozzle is rottedby a reaction force applied thereto by said eccentric jet; and means forimparting axial motion to said cleaning nozzle..Iaddend. .Iadd.
 5. Afilter according to claim 4 and wherein said means for imparting axialmotion includes means for automatic sensation of particleaccumulation..Iaddend. .Iadd.
 6. A filter according to claim 4 andwherein said means for imparting axial motion comprises automaticallyactuable means for imparting axial motion to said cleaningnozzle..Iaddend. .Iadd.
 7. A filter according to claim 4 and whereinsaid means for imparting axial motion comprises manually actuable meansfor imparting axial motion to said cleaning nozzle..Iaddend. .Iadd.
 8. Afilter according to claim 4 and wherein said source of fluid comprises asource of a fluid to be filtered..Iaddend. .Iadd.
 9. A filter accordingto claim 4 and wherein said filter element comprises a stack ofcooperating filter discs..Iaddend. .Iadd.
 10. A filter comprising:ahousing having an inlet and an outlet; a filter element disposed in saidhousing and having a central longitudinal axis, said filter elementhaving a central open area arranged along said longitudinal axis of saidfilter element, an inner surface surrounding said central open area andan outer surface, the outer surface defining an upstream side of thefilter element and the inner surface of the filter element defining thedownstream side of the filter element, and wherein said filter elementcomprises a stack of cooperating filter discs; a cleaning nozzle forblowing out particles accumulating on said filter discs, said cleaningnozzle being disposed within said central open area and communicatingwith a source of pressurized fluid; means for imparting rotation to saidcleaning nozzle by outletting an eccentrically directed fluid jet suchthat the cleaning nozzle is rotated by a reaction force applied theretoby said eccentric jet; and means for imparting axial motion to saidcleaning nozzle..Iaddend. .Iadd.
 11. A filter according to claim 10 andwherein said means for imparting axial motion includes means forautomatic sensation of particle accumulation..Iaddend. .Iadd.
 12. Afilter according to claim 10 and also comprising:a pair of end rings atthe opposite ends of said stack of filter discs, said end rings beingformed with a plurality of openings therethrough and an array ofaxially-extending rods passing through said openings in said enddiscs..Iaddend. .Iadd.
 13. A filter according to claim 10, and whereinsaid means for imparting axial motion comprises automatically actuablemeans for imparting axial motion to said cleaning nozzle..Iaddend..Iadd.
 14. A filter according to claim 10 and wherein said means forimparting axial motion comprises manually actuable means for impartingaxial motion to said cleaning nozzle..Iaddend. .Iadd.
 15. A filteraccording to claim 10 and wherein said source of fluid comprises asource of a fluid to be filtered..Iaddend. .Iadd.
 16. A filtercomprising:a housing having an inlet and an outlet; a filter elementdisposed in said housing and having a central longitudinal axis, saidfilter element having a central open area arranged along saidlongitudinal axis of said filter element, an inner surface surroundingsaid central open area and an outer surface, the outer surface definingan upstream side of the filter element and the inner surface of thefilter element defining the downstream side of the filter element; acleaning nozzle for emitting a pressurized fluid jet for cleaning saidfilter element and for emitting a fluid jet directed eccentricallyrelative to said longitudinal axis of said filter element so as to applya rotary moment to said fluid jet, said cleaning nozzle being disposedwithin said central open area and communicating with a source ofpressurized fluid; and means for imparting axial motion to said cleaningnozzle..Iaddend. .Iadd.
 17. A filter according to claim 16 and whereinsaid filter element comprises a stack of cooperating filterdiscs..Iaddend.